Suction cup



FIG. 1 is a perspective view of a suction cup according to the inventive design;

FIG. 2 is an elevational view of a suction cup according to the inventive design;

FIG. 3 is a top plan view of a suction cup according to the inventive design;

FIG. 4 is a perspective view of a suction cup according to the inventive design with the top portion depressed and in use;

FIG. 5 is an elevational view of a suction cup according to the inventive design with the top portion depressed and in use; and,

FIG. 6 is a top plan view of a suction cup according to the inventive design with the top portion depressed and in use. 

The ornamental design for a suction cup, as shown and described. 